Impact of complex coacervation on tau amyloid aggregation*

Amyloid aggregation of tau protein is implicated in human neurodegenerative diseases. While complex coacervation (CC) of tau and polyanion has shown both biological and pathological significance, its impacts on tau amyloid aggregation is not well understood. We report here recent findings and characterizations of tau-polyanion CC and its relationship with tau aggregation. We first demonstrate that tau can form complex coacervates with almost any polyanion. We found whether tau CC remains fluidic or solidifies towards fibrils is determined by the aggregation propensity of the CC forming constituents, not the CC forming process. Further, we closely examined changes of aggregation kinetics of tau resulting from the CC environment, and found the collision dependence of tau aggregation to be reduced by CC. Finally, we investigated the effect of CC on the fibrillization kinetics and seeding activity by tau fibrils.